Wing type dipole antenna with radiators of particular shape



Feb. 28, 1961 c, -rs, JR

WING TYPE DIPOLE ANTENNA WITH RADIATORS OF PARTICULAR SHAPE Filed D60. 23, 1957 F/Ei/ 63011170 PIA! MEWMTyZW WING TYPE DIPOLE ANTENNA WITH RADI- ATORS OF PARTICULAR SHAPE Chester B. Watts, Jr., Winchester, Mass., assignor to Andrew Alford, Boston, Mass.

Filed Dec. 23, 1957, Ser. No. 704,628

8 Claims. (Cl. 343-795) The present invention relates to a dipole.

The dipole of the present invention is designed particularly to provide a low standing wave ratio within a two to one operating frequency band when the dipole is mounted on a fiat metal sheet or a large metal cylinder, with the dipole presenting a particularly good match to a 50 ohm coaxial feeder.

A further object of the present invention is to provide a dipole antenna which may be cast or formed of a network of conductive rods of various cross sectional shapes for radiation of a selected frequency band, with points and intersecting to form imaginary diverging lines of substantially 90 or less.

These and other objects and advantages of the present invention will be more clearly understood when considered in connection with the accompanying drawings in which:

Figure l is a top plan view of the invention; and

Figure 2 is a side partially cross section elevation of the invention.

The dipole of the present invention is particularly adapted for use in connection with a scanner or variable delay lines for, as indicated, when it is mounted on a fiat metal sheet or a large metal cylinder, it presents a relatively good match to a 50 ohm coaxial feeder with a standing wave ratio at frequencies within a two to one operating frequency band of below about 1.5 or 1.6.

In this arrangement, there are provided two radiating members 1 and 2 similarly shaped and symmetrically arranged about a center longitudinal axis with the two members being coplanar. These members 1 and 2 form outwardly extending tapered radiating wings. Because of the similarity of the two members, only member 2 will be described in detail. This member 2 includes edges 7 and 8. Additionally, a V-shaped gap formed by the edge 3 with an imaginary vertex close to the feed point form an extension of the edge 8. Thus, the mass of the wings is arranged symmetrically about an imaginary axis intersecting near the point of feed and diverging from said point to form an angle of substantially 90 or less. As the antenna is in fact a dipole, edge 7 is substantially coplanar with the masses of the radiating wings extending radially inwardly from this edge whereby the axis of United States Patent ice symmetry of the radiating wings forms an angle of substantially 90 or less with edge 7. The plane of member 2 is bounded by six edges or sides 3, 4, 5, 6, 7 and 8 as well as opposing faces generally indicated at 9 and 10.. Member 1 is similarly formed as shown in the drawing. In order to obtain a voltage standing wave ratio of less than substantially 1.5 or 1.6 within a frequency band of two to one or as expressed in wave lengths where a=wavelength at arithmetic mean frequency,

the relative parameters indicated in the drawings should preferably be maintained, particularly in the design of the edges.

Thus, utilizing the ground plane 11 as the x axis, the projected height normal to the x axis of side 3 is .O98a. The length of side 4 is .03 3a. The length of side 5 projected onto the x axis is .2115a. The length of side 6 is .09822. The length of side 7 from side 6 to side 8, and through the feed, is .279a. The length of side '8 is .l34a. The overall height of the dipole from the ground plane is .46011. The width is .622a from end to end,

while the spacing of the members 1 and 2 from the g the dipole reduced in thickness so that less mechanical strain is placed upon the center portion.

- The members 1 and 2 are fed from an unbalanced coaxial line through a balanced three conductor feed arrangement which arrangement is made integral with mechanical supports of the dipole elements. These three conductor feed members comprise the legs 12, 13 and 14. As is known, it is inherent in conversions of this general type, that is, from an unbalanced coaxial mode to a balanced mode, that a four to one impedance transformation exists between the balanced and coaxial mode. This conversion takes place at the shorting post of the radiating elements and thus the coaxial mode may be considered as proceeding from the feeding coaxial line and up the three conductor structure 12, 13 and 14 as far as the shorting post of the radiating elements. The terminating impedance of the coaxial mode comprises two parts. The first part is one-fourth the balanced impedance of the radiating elements over the ground screen.

- The second part, in parallel with the first, is one-fourth of the reactance presented by the'three conductor structure, operating in the balanced mode, short circuited at the base.

In order to reduce the frequency dependence of the coaxial mode terminating impedance, this impedance was designed as a substantially constant impedance of approximately 17 ohmsv over a two to one frequency range. This 17 ohm impedance is transformed to a value closer to 50 ohms at the base of the dipole, or rather in the balanced line. This arrangement is obtained by lowering the characteristic impedance of the three conductor elements 12, 13 and 14 which is accomplished Patented Feb. 28, 1961 member 2. Both of these legsv as well as leg. 13.. are. rectangular in shape and have dimensions. equal to. the.

full thickness of the individual elements 1 and 2 at their thicker points. Leg 13, which extends. parallel to legs 12 and, 14, is connected to member- 1 at the bottom of side 8. It will be noted that the length of leg 13 is .1710. Legs 12 and 14 are integral with the base,15 which, as indicated. at Figure 1, may be square in shape with a series of screw holes 16 adapted to secure it to a ground sheet 11. The coaxial. lines which feed the dipole may be connected. to the end type plug 17 having inner conductor 18 and outer conductor 19, with outer conductor 19 suitably secured to the ground plane and the dipole itself; The inner conductor 18 insulated by insulating dielectric 20 is connected to the lower end of leg 13 through the series section 21.

While the foregoing relative dimensions are ideal, it will be noted that departures from them will normally increase the voltage standing wave ratios above the desired 1.5 or 1.6. Substantial variations may be incorporated as previously indicated in the outer portions of the members 1 and 2 insofar as thickness is. concerned. However, the thickness of the center portion is to; some extent critical.

the area enclosed by the dotted lines indicated at 26 affectsqthe low frequency of the band width transmitter. Variations therefore of the side edges inthese areas will. have effect respectively on the high. and low frequency portions of the band widths.

It may be noted that the center conductor 13 is con-- nected to one of the outer conductors at a point remotefrom the lower ends of the outer conductors.

Having now described my invention, I claim:

1. A dipole comprising a pair of coplanar radiators, each having a geometric configuration providing three continuous sides each normal to the adjacent one and two additional sides. tapering towards one another from said continuous sides and interconnected by a sixth side parallel, with the center one of said continuous sides, with one of said additional sides longer than. the other, and means feedingsaid radiators in phase opposition at corresponding points at substantially the intersection of twooi said continuous sides.

It will also be observed that the area substantially enclosed by dotted lines at 25 atfect the high frequency end of the band width transmitter while.

esteem 2. A dipole as set forth in claim 1 wherein the relative lengths of said sides include said center continuous side equals .279a,

said continuous side adjacent said intersection equals the other of said continuous sides equals .098a,

and said sixth side equals .033a

where a equals the wavelength at the arithmetic mean frequency of a desired frequency band.

3. A dipole as set forth, in claim 2 wherein said one and other additional sides. have lengths. projected onto a parallel with said other of said continuous sides of 2115a and .O98a respectively.

4. A dipole: as setforth in: claim 2 wherein the overall height of. the dipolefrorn the ground plane is .4601: and the width from end to end of said radiators is .622a.

5. A dipole as set forth. in claim 4- wherein said radiators have a thickness of between substantially .0171: and .05la.

6. A dipole as set forth in claim 2 wherein said means for. feeding said radiators comprises a four to one impedance transformation means.

7. A dipole comprising a pair of coplanar radiators each having a geometric configuration providing three continuous sides each normal to the adjacent one and two additional sides tapering toward one another from said continuous sides with one of said additional sides longer than the other, and means including impedance transformation means feeding said radiators in phase opposition at corresponding points at substantially the intersection of two of said continuous sides.

8. A dipole antenna comprising, a pair of wing structures, each wing structure having six edges, a first pair of opposing faces, a second pair of opposed faces extending from one of said edges toward another in parallel relationship, and a third pair of opposing faces connecting said first and second faces and converging from said first faces toward said second faces.

References Cited in the file of this patent UNITED STATES PATENTS 2,311,364 Bushbeck et al. Feb. 16, 1943 2,313,046 Bruce Mar. 9, 1943 2,433,183 Wolf Dec. 23, 1947 2,555,857 Nelson et a1. June 5, 1951 2,594,839 Alford Apr. 29, 1952 2,642,528 Albright June 16,1953 FOREIGN PATENTS 592,343 Great Britain Sept. 16, 1947 

